Free ring floating roof seal



Sept; 7, 1965 R. K. CADWELL FREE RING FLOATING ROOF SEAL 2 Sheets-Sheet 1 Filed 001;. 5, 1962 Can well I N VE N TOR.

WHANN a MCMA/V/GAL Af/orneys for Anal/cant Sept. 7, 1965 R. K. CADWELL 3,204,809

FREE RING FLOATING ROOF SEAL Filed Oct. 5, 1962 2 Sheets-Sheet 2 9 z. 7 MM 71 mm 3 +3 M 3mm f m u a mmm ml u a 6 Wm i 8 W e n u 3 K Mm h mm W W n & n n n n u 7 n "m": 4 t: 1 2/ 6 l 2 3 @m 2 3 u 2 7 .32 as 1 m 5 flX M m m. Mi

United States Patent.

3,204,809 FREE RING FLOATING ROOF SEAL Ralph K. Cadwell, Los Angcles, Calif, assignor to Lacy Manufacturing Company, Los Angeles, Calif., a corporation of California Filed Oct. 5, 1962, Ser. No. 228,648 4 Claims. (Cl. 220-26) This invention relates to a sealing means for a floating roof type storage tank and, more particularly, to a seal for sealing the annular space between the tank and roof and which is free of the roof so the root can move horizontally independently of the seal.

Tanks having floating roofs are usually large and are used to store petroleum products, liquid chemicals and, generally speaking, inflammable liquids. Hence, the desirability of a floating roof.

The roof is somewhat smaller in diameter than the interior of the tank and, thus, there is an annular gap between the exterior of the roof and the inner wall surface of the tank. The space or gap between the floating roof and the tank wall is sealed against the escape of product vapors or the entrance of foreign matters from above the roof.

In the prior art, the annular seals have presented substantial problems in that, as the tanks are generally quite large, the inner wall of the tank rarely has a true circular form and usually has many substantial irregularities.

It is .an object of the invention to provide an improved seal for tanks of the type having floating roofs.

It is another object of the invention to provide a seal for the annular space between a tank and its floating roof and which forms a good closure irrespective of irregularities in the inner surface of the tank.

It is still another object of the invention to provide a compressible and flexible seal of the type described in the preceding paragraph and which is not fixed to the roof, the roof being free to move horizontally independently of the seal and without compressing the seal material. As the roof can move horizontally independently of the seal, it is required that the seal be compressed only enough to seal around the irregularities of the tank shell, and this permits a minimum of wear. Further, by having the seal free of the roof, a better seal can be made against the tank wall with less compressive force between the seal and the wall than when the seal is fixed to the tank.

It is a further object of the invention to provide a seal of the type described in the preceding paragraph in which the seal is not affected by horizontal movement of the roof, as has been the case in the prior art.

It is a still further object of the invention to provide a seal of the type described in the preceding paragraphs and which can be removed from the tank and replaced independently of the roof.

It is another object of the present invention to provide a seal of the type described in the preceding paragraphs in which liquids are not required.

It is still another object of the invention to provide a seal of the type described in the preceding paragraphs and in which the seal is slidably engaged with the inner surface of the tank in a state of compression so as to have stored energy within the seal structure so as to continuously be forced into sealing engagement against the tank wall.

It is a further object of the invention to provide a seal for a floating roof in which the roof is free to move horizontally independently of the seal and in which means are provided to prevent the roof from contacting the structure supporting the seal.

It is a still further object of the present invention to provide a seal of the type described in the preceding parawherein small details have been described for the competence of disclosure, without intending to limit the scope of the invention which is set forth in the appended claims.

Referring to the accompanying drawings, which are for illustrative purposes only:

FIG. 1 is a fragmentary, partially cross sectioned plan view of a cylindrical tank having a floating roof and a seal between the roof and the inner surface of the wall of the tank, according to the invention;

FIG. 2 is a fragmentary, side elevational view of the tank roof and seal, taken as indicated along the line 22 of FIG. 1;

FIG. 3 is a fragmentary cross sectional view, taken as indicated along the line 33 of FIG. 2; 7

FIG. 4 is a fragmentary bottom view of the tank roof, taken as indicated along the line 44 of FIG. 2;

FIG. 5 is a fragmentary side elevational cross sectional view of another embodiment of the seal shown in FIG. 1;

FIG. 6 is a fragmentary side elevational view of the seal shown in FIG. 5, having an alternate form of means for vertically connecting the seal to the floating roof;

FIG. 7 is a side elevational view showing an alternate form of the invention shown in FIG. 6;

FIG. 8 is a fragmentary view, taken as indicated along the line 88 of FIG. 7;

FIG. 9 is a partially cross sectioned view, taken as indicated by the line 9-9 in FIG. 7.

Referring again to the drawings, there is shown a vertical cylindrical wall 10 of a tank 11, having a floating roof 12. The tank wall 10 is generally cylindrical and has an inner cylindrical vertical surface 13.

The floating roof 12 has a flat circular bottom 17, a vertical cylindrical wall or rim plate 18 and a flat circular top deck 19. The roof 12 is sealed so as to float in liquid in the tank. Its diameter is somewhat smaller than the diameter of the tank wall 10 so that an annular space 20 is provided therebetween.

In order that the floating roof be maintained centrally within the tank, centering devices 23 are provided on the roof bottom, extending radially outwardly, and being circumferentially spaced around the roof.

As may be seen in FIGS. 14, each centering device is comprised of a radially extending closed-ended channel member 24, pivotally secured by a bolt 25 to an upwardly opening channel member 26 welded to the bottom 17 of the roof. Secured to the vertically directed web 29 of the channel 24 is a radially extending leaf spring 30, having its inner end 31 loosely engaged in a downwardly opening slot 32 of a bracket 35, welded to the web bottom of the channel member 26. The centering devices 23 are provided in even numbers with alternating left and right-hand devices, 'as indicated in FIG. 1, where the lower roller 36 decreases in diameter in the upward direction and the upper roller 36 decreases in diameter in the lower direction. Thus, any lateral movement of the roof is restrained when the channel ends 34 move against the tank wall, so as to pivot the channels 24, and which are returned to their normal position by the action of the leaf springs 30.

Truncated cone-shaped rollers 36 are engaged for rotation with the bottom legs. of the channels 24. Each of the rollers 36 has a bolt axle 37 supporting an upwardly extending angle iron 33, welded to web 41 of outwardly opening, channel-shaped seal ring 42. The seal ring 42 is independent of the roof and is supported vertically by the circumfe-rentially spaced channels 24, the ring 42 being flexible enough to conform to any irregularities in the cylindrical wall 10 surrounding the ring.

Secured within the ring 42 is an annular resilient pad 43 under compression around the entire ring so as to have a stored energy force acting radially outwardly around the entire circumference of the tank. If the pad 43 were permitted to expend its entire stored energy, it would expand into the phantom line configuration 44, shown in FIG. 2. The pad '43 may be made of foam r sponge rubber or of a synthetic cellular material, such as Neoprene. -It also may be made of any sufiiciently resilient cellular plastic material. 7 Extending around the outer circumferential face of the pad 43 is a continuous annular sealing sheet 47 forming a seal and scuff :band, slidably and sealingly engaged with the inner surface 13 of the wall 10. The ban-d 47 is slidably engaged with the outer circumferential face of the pad and has its lower edge 48 circumferentially secured to the lower leg or wall of the channel 42 by bolts 49. The inner or upper edge 50 is circumferentially and sealingly secured to annular bolting flange 53 on the rim plate 18 by means of bolts 54 and annular band 55. The sealing sheet 47 may be made of rubber, synthetic rubber, asbestos, or some other sealing material that is chemi ca-lly inert to the liquid in the tank. As may be seen in FIG. 2, the bolting flange 53 is placed at the approximate liquid level in the tank so that a portion of the sheet 47 is submerged.

The stored energy force in the pad 43 forces the vertical portion 56 of the sealing sheet into sealing and slidable engagement with the cylindrical surface 13 of the wall, and being flexible, permits the seal to be effected on any irregularities that may occur in the wall. As the liquid level in the tank rises so as to cause the floating roof to move upwardly, the seal ring 42, although horizontally independent of the floating roof, i caused to move upwardly by the upward movement of the channels 24 in contact with the rollers 36. Similarly, when the liquid level in the tank is lowered, the seal ring 42 is also lowered as the result of the upper horizontal legs of the channels 24 making contact with the upper surface of the rollers 36. In either upper or lower movement, the outer face of the vertical portion of the ealing sheet moves on the inner surface of the tank wall, maintaining the seal in the annular space 20 between the tank wall and the floating roof.

As the distance between the outer end 34 of the channel 24 is shorter than the distance of the bolts 54 or the seal band 55 from the angle 38, the outer end 34 will make contact with the wall so that the belts or the band 55 will not contact the angle 38 when the floating roof moves horizontally. Whenever there is a lateral movement of the floating roof, some of the leaf springs 30 will actuate their respective channels 24 on the pivots 25 so as to restore the roof to a generally central position within the tank. That is, for example, referring to FIG. 1, if the tank moved radially in the direction of the lower centering device 23 in the drawing, the upper centering device would tend to pivot and the leaf spring would tend to return the roof and the centering devices to the normal positions.

From the foregoing, it is clear that since the seal ring 42 and the other sealing structure is independent of the horizontal movements of the floating roof, such movements do not disturb the seal and cause no wear on it. Further, the force in the compression pad 43 must be sufiicient to hold the sheet 47 in sealing engagement with the tank wall, and this force is considerably less than that that would be required if the force were related to the entire floating roof. This also reduces the wear on the seal in its vertical movements.

As shown in FIG. 2, at the upper end of the floating roof, circumferentially secured to the top of the rim plate 18, is a fabric weather strip 59, biased into conical shape by spring member 60 so that upper end 61 maintains contact with the tank wall surface 13. The weather 4 strip 59 prevents nain Water and other foreign matter from entering the annular space 20.

An alternate embodiment of the invention, shown in FIG. 2, is shown in FIG. 5 where the compressed annular pad 43 is held within the channel 42, the latter being supported by downwardly and inwardly directed, circumferentially spaced angle irons 62 having the rollers 36 on their lower ends. In this embodiment, the sealing sheet 65, basically equivalent to the sheet 47, has its upper circumferential edge '66 sealingly secured to the upper leg or wall of the channel 42 by bolts 67 and circumferential sealing band 68. The sheet is loosely fitted above and below the pad 43 to permit sliding movement therewith and has a lower portion 71 circumferentially and sealingly secured to the lower leg or wall of the channel 42 by means of circumferentially spaced bolts 7-2 and annular band 73. The sheet :65 extends radially inwardly from the lower portion 71, having its inner edge 74 sealingly secured to bolting flange 7-7 on the rim plate 18.

This embodiment permits access to the bolts securing the inner edge 74 to the bolting flange 77 so that, under certain circumstances the ring and sealing sheet could be removed from the tank without removing the roof.

In FIG. 6, there is shown the same ring, pad and sheet arrangement as is shown in FIG. 5, but there are different centering and vertical support devices in the form of circumferentially spaced torsion bars 78. The bars 78 are supported vertically at their upper ends by means of circumferentially spaced brackets 79, secured to the outer surface of the rim plate 18, and the lower ends of the torsion bars are secured to circumferentially spaced brackets 80 on the inner circumferential surfaces of the ring 42.

The bars 78 permit horizontal movement of the floating roof independently of the seal ring and seal, and also center the roof within the tank. As the roof moves toward one wall portion, as may be visualized in FIG. 6, the bar 78 would tend to restrain such movement and the bracket 79 would limit the movement by making contact against the tank wall. The bracket 79 is extended out far enough so that it will contact the shell surface 13 before the roof will contact the sealing structure. Similarly, the bars 78 would restrain any movement of the floating roof, as shown in FIG. 6, toward the viewer.

In FIG. 6, the securing nuts on the bar 78 are shown to hold the bar tightly on the brackets 79 and 80. When no spring effect is desired in the bar, a mild seal bar can be used with the nuts in a loose relationship with the brackets, and in such a structure the bar 78 will act only as a vertical support for the ring 42 and not as a centering device for the roof. If the bars 78 are not provided to act as centering devices, conventional ones, having a guide roller in contact with the tank wall and supported radially by a spring for the centering of the roof, as shown in FIGS. 5 and 6 of the United States Patent No. 2,735,573, may be attached to the bottom of the floating root.

In FIGS. 7, 8 and 9, the sealing structure, as shown in FIG. 6, is supported vertically by circumferentially spaced leaf springs 81. The upper ends of the leaf springs are pivotally secured to circumferentially spaced brackets 82 on the floating roof rim plate. The pivoting of the upper ends of the springs 81 permits the roof to rotate and this rotation is limited, as shown in FIGS. 8 and 9, by the vertical stop members 83 on opposite sides of each of the springs 81.

The lower ends of the springs 81 are fixedly secured to the ring 42 on circumferentially spaced brackets 84. The springs 81, supporting the sealing structure vertically, permit independent horizontal movement of the floating roof with respect to the seal, both rotationally and laterally. In either case, the springs 81 limit the movement so that they wil not permit the roof to contact the spring structure. If it is desired, additional conventional 5 centering devices can be secured to the roof to further restrict its horizontal movement, as indicated in regard to the structure shown in FIG. 6.

The invention and its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts of the invention without departing from the spirit and scope thereof or sacrificing its material advantages, the arrangement hereinbefore described being merely by way of example, and I do not wish to be restricted to the specific form shown or uses mentioned, except as defined in the accompanying claims, wherein various portions have been separated for clarity of reading and not for emphasis.

I claim:

1. In a tank having a generally cylindrical vertical wall and having a floating roof, a seal extending in an annular space between the wall and roof and forming a seal therebetween, said seal comprising:

(a) means extending from said roof supporting a ring surrounding and being spaced from said roof in said annular space, said roof being movable horizontally independently of said ring, said ring being free of the affects of the horizontal movement of said roof,

(b) said ring having an outwardly opening channelshaped cross section;

(c) a flexible sealing sheet extending over the opening of said channel of said ring and being sealingly secured to and around the periphery of said roof,

((1) said sheet being secured to and around said ring adjacent its periphery;

(e) an annular resilient pad of compressible cellular material secured within the channel of said ring and radially inwardly of said sheet,

(f) said pad being in compression so as to bias said sheet radially outwardly against the wall of said tank to form a seal thereon; and

(g) means extending from said roof to prevent the roof from horizontally directly and indirectly contacting said ring.

2. In a tank having a generally cylindrical vertical wall and having a floating roof, a seal extending in an annular space between the wall and roof and forming a seal therebetween, said seal comprising:

(a) means extending from said roof supporting a ring surrounding and being spaced from said roof in said annular space, said roof movable horizontally independently of said ring, said ring being free of the affects of said horizontal movement of said roof,

(b) said ring having an outwardly opening channelshaped cross section;

() a flexible sealing sheet extending over the opening of said channel of said ring and being sealingly secured to and around the periphery of said roof,

(d) said sheet being secured to and around an under peripheral portion of said ring; and

(e) an annular resilient pad of compressible cellular material secured within the channel of said ring and radially inwardly of said sheet,

(f) said pad being in compression so as to bias said sheet radially outwardly against the wall of said tank to form a seal thereon.

3. In a tank having a generally cylindrical vertical wall and having a floating roof, a seal extending in an annular space between the wall and roof and forming a seal therebetween, said seal comprising:

(a) a ring in said annular space radially outwardly of said roof,

(b) said ring having an outwardly opening channelspaced cross section;

(c) a flexible sealing sheet extending over the opening of said channel of said ring and being sealingly secured to and around the periphery of said roof,

(d) said sheet being secured to and around said ring adjacent its periphery;

(e) an annular resilient pad of compressible cellular material secured within the channel of said ring and radially inwardly of said sheet,

(f) said pad being in compression so as to bias said sheet radially outwardly against the wall of said tank to form a seal thereon;

(g) circumferentially spaced roller track members extending radially outwardly from said roof and being pivotally secured thereto;

(h) spring means on each member to limit the pivotability thereof,

(i) each of said members having an outer end spaced from said tank wall a distance shorter than said roof, radially adjacent thereto, is from said ring so that when said roof is moved horizontally it will not contact said ring; and

(j) rollers, circumferentially spaced, corresponding to said track members, having horizontal axes and secured to and depending from said ring so that each of said rollers is supported vertically to roll horizontally in a respective track member.

4. In a tank having a generally cylindrical vertical wall and having a floating roof adapted for horizontal and vertical movement, a seal extending in an annular space between the wall and roof and forming a seal therebetween, said seal comprising:

(a) a ring in said annular space being spaced radially outwardly of said roof,

(b) said ring having an outwardly opening channelshaped cross section;

(c) a flexible sealing sheet extending over the opening of said channel of said ring and being sealingly secured to and around the periphery of said roof,

(d) said sheet being secured to and around said ring adjacent its periphery;

(e) an annular resilient pad of compressible cellular material secured within the channel of said ring and radially inwardly of said sheet,

(f) said pad being in compression so as to bias said sheet radially outwardly against the wall of said tank to form a seal thereon; and

(g) circumferentially spacer, generally vertically directed spring means having one end connected to said roof and having the other end thereof connected to said ring to support said ring vertically with respect to said roof and to prevent said roof from directly and indirectly contacting said ring in a horizontal movement, said roof being movable horizontally independently of said ring, said ring being free of the affects of said horizontal movement of said roof.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 8/62 Canada.

THERON E. CONDON, Primary Examiner.

EARLE J. DRUMMOND, GEORGE O. RALSTON,

Examiners. 

1. IN A TANK HAVING A GENERALLY CYLINDRICAL VERTICAL WALL AND HAVINGA FLOATING ROOF, A SEAL EXTENDING IN AN ANNULAR SPACE BETWEEN THE WALL AND ROOF AND FORMING A SEAL THEREBETWEEN, SAID SEAL COMPRISING: (A) MEANS EXTENDING FROM SAID ROOF SUPPORTING A RING SURROUNDING AND BEING SPACED FROM SAID ROOF IN SAID ANNULAR SPACEL SAID ROOF BEING MOVABLE HORIZONTALLY INDEPENDENTLY OF SAID RING, SAID RING BEING FREE OF THE AFFECTS OF THE HORIZNTAL MOVEMENT OF SAID ROOF, (B) SAID RING HAVING AN OUTWARDLY OPENING CHANNELSHAPED CROSS SECTION; 